DE-102024132804-A1 - Methods for the production and conditioning of electrode mixtures and of dry electrodes from the electrode mixtures

Abstract

The present invention relates to a method for producing and conditioning an electrode mixture consisting of active material, optionally additives and binder, comprising the steps 1) Producing the electrode mixture in a mixing vessel, wherein during the production the mixture is heated to a temperature TH, where TH > 45°C, 2) Cooling the electrode mixture in the mixing container by at least ΔT = 5°C and preferably to a temperature TMAX < 35°C, but not below a sampling temperature TE > 24°C, 3) Extraction of the electrode mixture at the extraction temperature and feeding of the electrode mixture to a cooling device, 4) Cooling the electrode mixture after step 2) by at least 4°C, preferably to a temperature TK < 19°C using the cooling device.

Inventors

• Stefan Gerl

Assignees

• MASCHINENFABRIK GUSTAV EIRICH GMBH & CO KG

Dates

Publication Date

20260513

Application Date

20241111

Claims (8)

1. A method for producing and conditioning an electrode mixture consisting of active material, optionally additives and binder, comprising the steps: 1) producing the electrode mixture in a mixing vessel, wherein during production the mixture is heated to a temperature T_H, where T_H>45°C; 2) cooling the electrode mixture in the mixing vessel by at least ΔT = 5°C and preferably to a temperature T _MAX < 35°C, but not below a withdrawal temperature T_E>24°C; 3) withdrawing the electrode mixture at the withdrawal temperature and feeding the electrode mixture to a cooling device; 4) cooling the electrode mixture after step 2) by at least 4°C, preferably to a temperature T_K < 19°C, using the cooling device.
2. Procedure according to Claim 1 , characterized in that a conveying line of a pneumatic conveying system for removing the electrode mixture from the mixing container, which is operated with a gas, preferably with a temperature T G < 19°C, is provided as a cooling device in steps 3) and 4), wherein preferably in step 2), between steps 2) and 3) and/or during step 3) dry ice or liquefied gas is introduced into the mixing container, and the gas produced by sublimation or evaporation is directed into the conveying line.
3. Procedure according to Claim 1 or 2 , characterized in that the electrode mixture according to step 2) is transferred into a buffer container, wherein preferably the buffer container is temperature-controlled and is used as a cooling device in steps 3) and 4), wherein the buffer container is preferably double-walled, wherein a cooling fluid can flow between the two walls, and/or the buffer container has thermal insulation, wherein the electrode mixture is particularly preferably moved in the buffer container.
4. Method according to one of the preceding claims, characterized in that the electrode mixture according to step 3) is applied to a sieve and only sieve passage is used as conditioned electrode mixture, wherein preferably the sieve has a mesh size of less than 10 mm and particularly preferably of less than 5 mm and best of less than 2 mm.
5. Procedure according to Claim 4 characterized in that the sieve overflow is directed into the mixing container, the buffer container, a crushing device or into the conveying line.
6. Procedure according to Claim 4 , characterized in that a friction sieve or, more preferably, an eddy current sieve is used as the sieve, wherein the use is preferably carried out in such a way that no sieve overflow remains.
7. A method for producing dry electrodes from electrode mixtures produced by a method according to one of the preceding claims, characterized in that the electrode mixture is fed to a calender and calendered into a web, wherein the edge strips of the web or excess material are then cut off to ensure a uniform width of the web, and the cut-off edge strips or excess material are fed into the mixing vessel, the buffer vessel or into the conveying line.
8. Procedure according to Claim 7 , characterized in that a comminution device is provided which divides the separated edge strips into smaller strip sections.

Description

The present invention relates to a method for producing and conditioning dry electrode mixtures. Furthermore, the present invention relates to a method for producing dry electrodes from these electrode mixtures. In recent years, battery technology, and in particular lithium-ion technology, has moved into the spotlight, as it is essential for the functionality of, for example, fully electric vehicles, but also for stationary energy storage systems. A long-lasting, high-capacity battery that is cost-effective to manufacture is a prerequisite for the acceptance of fully electric vehicles. Currently, lithium-ion batteries are predominantly used. Within this category, several specific cell chemistries dominate, with the following being the most widespread cathode materials: • Nickel-manganese-cobalt (NMC) electrode mixture: These cells use a mixture of nickel, manganese, and cobalt. The nickel ensures high energy density, manganese provides thermal stability, and cobalt stabilizes the structure. • Nickel-cobalt-aluminum (NCA) electrode mixture: This mixture contains nickel, cobalt, and aluminum in the cathode. The aluminum content stabilizes the structure and improves the lifespan, while nickel maximizes the energy density. • Lithium iron phosphate (LFP) electrode mixture: In this cobalt-free cell chemistry, lithium iron phosphate is used as the cathode material, which is less energy-dense but offers a longer lifespan and better thermal stability. The anodes usually consist of graphite or silicon-graphite mixtures. For all these types, electrode mixtures are produced using polymeric binders, sometimes also with conductive additives, applied to conductive foils, and calendered during or after this process to optimize the structural integrity and density of the electrodes. Furthermore, there are developments that could play a significant role in the future. Besides more cost-effective, but lower-performing, cobalt-free sodium-ion cell chemistries, intensive research is also being conducted on all-solid-state batteries with solid electrolytes. This technology theoretically offers an even higher energy density than conventional lithium-ion batteries and, due to the solid electrolyte, even greater safety. The production of all these batteries will likely continue to require calendered electrodes, which present various calendering challenges. In summary, the calendering of electrode mixtures will continue to play an important role in future battery technologies, as it optimizes the density, homogeneity, and mechanical properties of the electrodes. However, the specific materials that will be used will depend on advances in materials science and the requirements of electromobility. A typical lithium-ion cell electrode consists of a copper foil acting as the anode and an aluminum foil acting as the cathode. The foils are usually coated on both sides with active material and, at least for the cathode, with additives. The electrodes must meet high standards in order to produce a reliable, high-capacity lithium-ion battery. The electrode layer must have a defined, constant thickness and a defined pore structure into which the electrolyte can penetrate to transport lithium ions to each particle of the active material. Ideally, the active material should be wetted by the electrolyte over as large an area as possible. Furthermore, the particles of the active material must be electrically connected to the metal foil, i.e., in the described example, to the copper or aluminum foil, to ensure the transport of electrons to and from each particle of the active material. Furthermore, the particles of the active material must be bound both to each other and to the metal foil, for which a binder material is used. Finally, the layer thickness should be as uniform as possible across the width and length. To produce the layers, the starting materials—that is, the active material, the binder, and any additives—must be mixed together and dispersed into a so-called "slurry" (paste). Typically, a liquid solvent (e.g., water or N-methyl-2-pyrrolidone (NMP)) is added, which then has to be removed again in complex drying processes after the electrode mixture has been applied to the film. The voids that form during the drying process are filled during the subsequent calendering. The fermentation process compresses the body to a defined porosity. The predominant wet processing of electrodes is time-consuming and energy-intensive. Furthermore, the automated production of electrode mixtures usually requires bulky drying equipment. There are also approaches to producing electrode mixtures dry, i.e., with little or even no solvent. However, this requires more intensive preparation of the components during mixing to convert the polymeric binders, which are no longer soluble in a solvent, into a processable and bondable state. Especially when PTFE or PVDF is used as a binder, the mixture typically needs to be processed in successive steps at different